Field of the Invention
The invention relates to a method and a radio set for transmitting messages over a communication network, in particular over a mobile radio system, and to a control device for controlling the transmission.
In order to ensure the most flexible and efficient use as possible of transmission capacities, messages are transmitted in many communication networks in the form of data packets. For example, in a global system for mobile communication (GSM) mobile radio system messages to be transmitted are packed in data packets, so-called bursts, and subsequently transmitted via an air interface.
Use is frequently made of a multiple access method in order to be able to separate the data packets and to allocate them to a specific connection or to a corresponding subscriber. For this purpose, use is made in the GSM of a combination of time division multiple access (TDMA) and frequency division multiple access (FDMA). In FDMA, the frequency band is decomposed into a plurality of frequency channels of the same size. The frequency channels are divided into eight time slots by the time division multiple access TDMA. The eight time slots of the frequency channel are combined to form a TDMA frame, the same time slots producing a physical channel in succeeding frames.
The physical channels and/or the corresponding data packets are assigned to logic channels according to a fixed scheme. Two types are distinguished in principle as regards the logic channel: signaling channels for transmitting signaling information, and traffic channels for transmitting useful data.
In order to be able to transmit messages, in particular speech by the limited transmission capacities of an air interface as efficiently as possible, the messages which are to be transmitted are compressed before transmission by source coding and protected against channel errors by channel coding. Different methods are known in this case, particularly for speech coding. Thus, for example, in the GSM speech can be coded by a full rate speech codec, a half rate speech codec or an enhanced full rate speech codec, in which case the speech codecs or the frame conditions required for them were already known, or were to be foreseen in the standardization.
In the meantime, progress in speech coding theory has led to the development of new speech codecs that can be used for even more efficient and/or flexible transmission of speech. These are, for example, so-called adaptive multirate speech codecs whose characteristics can be matched to the transmission characteristics of the transmission channel. Within the framework of this application, a speech codec is designated as a method for encoding and/or for corresponding decoding which can also contain source and/or channel coding.
In the standardization, laying down and definition of a transmission method, in particular the GSM standard, the types of information which are transmitted by individual bit positions of a data packet, or the purpose of the information transmitted by the individual bit positions are precisely laid down so that the information can be processed and used at the receiver as intended.
It is accordingly an object of the invention to provide a method and a radio set for transmitting messages that overcome the above-mentioned disadvantages of the prior art methods and devices of this general type, which permits as efficient and flexible a utilization as possible of limited transmission capacities, in particular within an already existing and/or standardized transmission method and, if appropriate, in accordance with appropriately standardized signaling channels.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for transmitting messages. The method includes performing a transmission on a basis of data packets, a respective data packet having a plurality of bit positions assigned to different types of information. A bit group structure is produced by information type-specific combinations of the bit positions to form bit groups within the respective data packet. The data packets having identical bit group structures are allocated to different types of logic channels. A bit group of the respective data packet, which is not required for an assignment to one of the logic channels, is used for transmitting a different type of information other than a type of information specific to the bit group.
Thus, the invention is based on the idea of using bit groups of a data packet which are not required in assigning the bit groups to a specific logic channel for transmitting a type of information specific to the bit group for the purpose of transmitting a different type of information. In particular signaling information, the importance of which could not yet have been recognized when the data packets or the bit group structure thereof was being defined, or the transmission of which was not yet regarded as necessary when laying down the transmission standard.
As a result of this, it is possible to employ new technical developments for improved use of transmission capacities even after the definition of a transmission method, for example by standardization.
When introducing the invention into a transmission method in accordance with the GSM standard, the stealing flag bit group of a normal burst data packet can be used in assigning the normal burst data packet to a slow associated control channel for transmitting new signaling information, in particular for transmitting information via a speech codec used in transmitting speech data.
As a result, even recent developments and findings of information and communication technology can be used in order to fashion more efficiently and flexibly the transmission of messages using a transmission method laid down such as the GSM standard.
In accordance with an added feature of the invention, there are the steps of basing a transmission method on one of a global system for mobile communication standard and a standard derived from the global system for mobile communication; and using a stealing flag bit group of the respective data packet which is a normal burst data packet to assign the respective data packet to a slow associated control channel for transmitting the different type of information other than the type of information specific to the bit group.
In accordance with an additional feature of the invention, there is the step of using a stealing flag bit group of the respective data packet, which is a normal burst data packet, to assign the respective data packet to a slow associated control channel for transmitting signaling information via a speech codec which is applied in transmitting data over a traffic channel assigned to the slow associated control channel.
In accordance with another feature of the invention, there is the step of using an adaptive multi-rate speech codec as a speech codec for a traffic channel in addition to a half rate speech codec, a full rate speech codec, and/or an enhanced full rate speech codec.
With the foregoing and other objects in view there is further provided, in accordance with the invention, a radio set formed of a first means for transmitting messages on a basis of data packets. A respective data packet has a plurality of bit positions assigned different types of information, and a bit group structure is produced by an information type-specific combination of the bit positions to form bit groups within the respective data packet. A second means is provided for assigning the data packets having identical bit group structures to different types of logic channels. A third means is provided for using a bit group of the respective data packet, which is not required for assignment to a logic channel, for transmitting the type of information specific to it to transmit a different type of information.
In accordance with an added feature of the invention, there is provided a fourth means for transmitting messages in accordance with one of a global system for mobile communication standard and a standard derived from the global system for mobile communication standard. A fifth means is provided for using a stealing flag bit group of a respective data packet which is a normal burst data packet in assigning the respective data packet to a slow associated control channel for transmitting the different type of information than the type of information specific to it.
In accordance with a further feature of the invention, there is provided a means for using a stealing flag bit group of the respective data packet which is a normal burst data packet in assigning the respective data packet to a slow associated control channel for transmitting signaling information via a speech codec used in transmitting speech data over a traffic channel assigned to the slow associated control channel.
In accordance with a another further feature of the invention, there is provided a means for speech coding on a basis of a half rate speech codec, a full rate speech codec, an enhanced full rate speech codec, and/or an adaptive multirate speech codec.
With the foregoing and other objects in view there is additionally provided, in accordance with the invention, a communications system which is formed of a radio set, as defined above, and a control device assigned to the radio set for controlling a transmission of the messages.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method and a radio set for transmitting messages, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.